diff --git a/src/objective-c/GRPCClient/private/GRPCSecureChannel.m b/src/objective-c/GRPCClient/private/GRPCSecureChannel.m
index c783462dd3056e26df887772784c33d162b33532..eb3cfc40eb0e818128ac436ec3f40bf6b666f0b9 100644
--- a/src/objective-c/GRPCClient/private/GRPCSecureChannel.m
+++ b/src/objective-c/GRPCClient/private/GRPCSecureChannel.m
@@ -33,7 +33,7 @@
 
 #import "GRPCSecureChannel.h"
 
-grpc_credentials *CertificatesAtPath(NSString *path) {
+static grpc_credentials *CertificatesAtPath(NSString *path) {
   NSData *certsData = [NSData dataWithContentsOfFile:path];
   NSCAssert(certsData.length, @"No data read from %@", path);
   NSString *certsString = [[NSString alloc] initWithData:certsData encoding:NSUTF8StringEncoding];